Current methods for injecting small amounts of material are problematic. One solution has been to use micrometer heads along with a syringe to deliver precise small amounts of fluid from a syringe. There are, however, problems with this current technology. Firstly, while commercially available micrometer heads allow for the plunger of a syringe to be depressed, they do not contain a mechanism to “pull back” the plunger in order to aspirate discreet amounts of fluid into a syringe. Secondly, the design of standard micrometer/syringe systems leads to a large arrangement that is unwieldy to operate and often requires two hands to operate, one to hold the syringe steady, the other to operate the micrometer head. The present invention provides a new micrometer assembly that overcomes these problems.
Another problem with injecting small amounts of material such as cells, is the damage that is done to the material when it is injected. When small amounts of cells are injected, the aspiration of cells into a syringe often causes damage to the morphology of the cells, which can impact their viability when injected into a host. Furthermore, when only small amounts of material are injected, the removal of the needle injecting the material can often “pull back” some of the material out of the injection site when removed. The present invention provides new delivery assemblies and methods which overcome these problems.